学习ASP.NET Core Razor 编程系列十三——文件上传功能（一）

using Microsoft.AspNetCore.Http;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Threading.Tasks;
 

namespace RazorMvcBooks.Models
{
    public class FileUpload
    {

        [Required]
        [Display(Name = "文件名")]
        [StringLength(60, MinimumLength = 3)]
        public string FileName { get; set; } 

        [Required]
        [Display(Name = "公共描述")]
        public IFormFile UploadPublicDescribe { get; set; } 

        [Required]
        [Display(Name = "后台描述")]
        public IFormFile UploadPrivateDescribe { get; set; }
    }

}

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using RazorMvcBooks.Models;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.IO;
using System.Linq;
using System.Net;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace RazorMvcBooks.Utils
{
    public class FileHelpers
    {
        public static async Task<string> ProcessFormFile(IFormFile formFile, ModelStateDictionary modelState)
        {
            var fieldDisplayName = string.Empty;

            // 使用反射获得的IFormFile实例对象的文件名称。
            // 如果名称没有找到，将会有一个简单的错误消息，但不会显示文件名称
            MemberInfo property =
                typeof(FileUpload).GetProperty(formFile.Name.Substring(formFile.Name.IndexOf(".") + 1));

            if (property != null)
            {
                var displayAttribute =
                    property.GetCustomAttribute(typeof(DisplayAttribute)) as DisplayAttribute;

                if (displayAttribute != null)
                {
                    fieldDisplayName = $"{displayAttribute.Name} ";
                }
            }

            //使用path.GetFileName获取一个带路径的全文件名。
            //通过HtmlEncode进行编码的结果必须在错误消息中返回。 
            var fileName = WebUtility.HtmlEncode(Path.GetFileName(formFile.FileName));

            if (formFile.ContentType.ToLower() != "text/plain")
            {
                modelState.AddModelError(formFile.Name,
                                         $"The {fieldDisplayName}file ({fileName}) must be a text file.");
            }


            //校验文件长度，如果文件不包含内容，则不必读取文件长度。
            //此校验不会检查仅具有BOM（字节顺序标记）作为内容的文件，
            //因此在读取文件内容后再次检验文件内容长度，以校验仅包含BOM的文件。
            if (formFile.Length == 0)
            {
                modelState.AddModelError(formFile.Name, $"The {fieldDisplayName}file ({fileName}) is empty.");
            }
            else if (formFile.Length > 1048576)
            {
                modelState.AddModelError(formFile.Name, $"The {fieldDisplayName}file ({fileName}) exceeds 1 MB.");
            }
            else
            {
                try
                {
                    string fileContents;

                    //使用StreamReader按UTF-8编码读取文件。
                    //如果上传文件是采用其他的编码。
                    //请使用32位编码，将UTF8Encoding改为UTF32Encoding
                    using (
                        var reader =
                            new StreamReader(
                                formFile.OpenReadStream(),
                                new UTF32Encoding(),
                                detectEncodingFromByteOrderMarks: true))
                    {
                        fileContents = await reader.ReadToEndAsync();

                        // 检查文件长度，如果文件的唯一内容是BOM，在删除BOM后内容实际上是空的。
                        if (fileContents.Length > 0)
                        {
                            return fileContents;
                        }
                        else
                        {
                            modelState.AddModelError(formFile.Name,
                                                     $"The {fieldDisplayName}file ({fileName}) is empty.");
                        }
                    }
                }
                catch (Exception ex)
                {
                    modelState.AddModelError(formFile.Name,
                                             $"The {fieldDisplayName}file ({fileName}) upload failed. " +
                                             $"Please contact the Help Desk for support. Error: {ex.Message}");
                    // Log the exception
                }
            }

            return string.Empty;
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Threading.Tasks;
 

namespace RazorMvcBooks.Models
{

    public class Describe
    {

        public int ID { get; set; }

  [Display(Name = "文件名称")]
        public string Name { get; set; }
  [Display(Name = "公共描述")]
        public string PublicDescribe { get; set; }
 

        [Display(Name = "公共描述大小(bytes)")]
        [DisplayFormat(DataFormatString = "{0:N1}")]
        public long PublicScheduleSize { get; set; }
 
        [Display(Name = "后台描述")]
        public string PrivateDescribe { get; set; }
 

        [Display(Name = "后台描述大小 (bytes)")]
        [DisplayFormat(DataFormatString = "{0:N1}")]
        public long PrivateScheduleSize { get; set; }
 

        [Display(Name = "上传时间(UTC)")]
        [DisplayFormat(DataFormatString = "{0:F}")]
        public DateTime UploadDateTime { get; set; }

    }

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;

namespace RazorMvcBooks.Models
{
    public class BookContext:DbContext
    {
        public BookContext(DbContextOptions<BookContext> options)
                : base(options)
        {
        } 

        public DbSet<Book> Book { get; set; }
        public DbSet<Describe> Describe { get; set; } 

    }
}